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Eigenvalues of a simple rotating flexible disk-shaft system are obtained using different methods. The shaft is supported radially by non-rigid bearings, while the disk is situated at one end of the shaft. Eigenvalues from a finite element and a multi-body dynamic tool are compared against an established analytical formulation. The Campbell diagram based on natural frequencies obtained from the tools differ from the analytical values because of oversimplification in the analytical model. Later, detailed whirl analysis is performed using AVL Excite multi-body tool that includes understanding forward and reverse whirls in absolute and relative coordinate systems and their relationships. Responses to periodic force and base excitations at a constant rotational speed of the shaft are obtained and a modified Campbell diagram based on this is developed. Whirl of the center of the disk is plotted as an orbital or phase plot and its rotational direction noted.

A new multi-scale curved beam based model was developed for piston-ring designs. This tool is able to characterize the behavior of a ring with any cross section design. This paper describes the conformability and ring static twist calculation. The conformability part model the static behavior of the ring in working engine conditions. The model employs the computation scheme that separates the meshing of the structure and local force generation. Additional to the conventional static ring-bore conformability analysis, the conformability model is designed to examine ring-bore and ring-groove interactions in a running engine under varying driving forces and localized lubrication conditions. We made Improvements on the way to handle the effects of the radial temperature gradient compared to the existing models. Examples are given on the effects of ring rotation on the interaction of the ring and a distorted bore as well as the change of local lubrication conditions.

A new multi-scale curved beam based model was developed for piston-ring designs. This paper describes the free-shape, force in circular bore and closed shape within a flexible band (ovality) related parts. Knowing any one of these distributions, this model determines the other two. This tool is useful in the sense that the characterization of the ring is carried out by measuring its closed shape within a flexible band which is more accurate than measuring its free shape or force distribution in circular bore. Thus, having a model that takes the closed shape within a flexible band as an input is more convenient and useful based on the experiments carried out to characterize the ring.

This paper presents the results of a study of how people interacted with a production voice-command based interface while driving on public roadways. Tasks included phone contact calling, full address destination entry, and point-of-interest (POI) selection. Baseline driving and driving while engaging in multiple-levels of an auditory-vocal cognitive reference task and manual radio tuning were used as comparison points. Measures included self-reported workload, task performance, physiological arousal, glance behavior, and vehicle control for an analysis sample of 48 participants (gender balanced across ages 21-68). Task analysis and glance measures confirm earlier findings that voice-command interfaces do not always allow the driver to keep their hands on the wheel and eyes on the road, as some assume.

The field of automotive engineering has devoted much research to reduce fuel consumption to attain sustainable energy usage. Friction reductions in powertrain components can improve engine fuel economy. Quantitative accounting of friction is complex because it is affected by many physical aspects such as oil viscosity, temperature, surface roughness and component rotation speed. The purpose of this paper is two-fold: first, to develop a useful tool for evaluating the friction in engine and accessories based on test data; second, to exercise the tool to evaluate the fuel economy gain in a drive cycle for several friction reduction technologies.

The aim of this study was to explore if fingernail delamination injury following EMU glove use may be caused by compression-induced blood flow occlusion in the finger. During compression tests, finger blood flow decreased more than 60%, however this occurred more rapidly for finger pad compression (4 N) than for fingertips (10 N). A pressure bulb compression test resulted in 50% and 45% decreased blood flow at 100 mmHg and 200 mmHg, respectively. These results indicate that the finger pad pressure required to articulate stiff gloves is more likely to contribute to injury than the fingertip pressure associated with tight fitting gloves.

To address the growing need for detailed chemistry in engine simulations, new software tools and validated data sets are being developed under an industry-funded consortium involving members from the automotive and fuels industry. The results described here include systematic comparison and validation of detailed chemistry models using a wide range of fundamental experimental data, and the development of software tools that support the use of detailed mechanisms in engineering simulations. Such tools include the automated reduction of reaction mechanisms for targeted simulation conditions. Selected results are presented and discussed.

One of the goals of designing engineering systems is to maximize the system's reliability. A reliable system must satisfy its functional requirements without failure throughout its intended lifecycle. The typical means to achieve a desirable level of reliability is through preventive maintenance of a system; however, this involves cost. A more fundamental approach to the problem is to maximize the system's reliability by preventing failures from occurring. A key question is to find mechanisms (and the means to implement them into a system) that will prevent its system range from going out of the design range. Functional periodicity is a means to achieve this goal. Three examples are discussed to illustrate the concept. In the new electrical connector design, it is the geometric functional periodicity provided by the woven wire structure. In the case of integrated manufacturing systems, it is the periodicity in scheduling of the robot motion.

Human explorers of planetary surfaces would benefit greatly from a spacesuit design that facilitates locomotion. To aid in the development of such an extravehicular activity suit, a design effort incorporating the concept of mechanical counter pressure (MCP) was undertaken. Three-dimensional laser scanning of the human body was used to identify the main effects of knee flexion angle on the size and shape of the leg. This laser scanning quantified the changes in shape that must be supported by an MCP garment and the tension that must be developed to produce even MCP. Evaluation of a hybrid-MCP concept using inextensible materials demonstrated strong agreement between experimental data and a mathematical model with rigid cylinder geometry. Testing of a form-fitting garment on the right lower leg of a subject demonstrated successful pressure production. Further research is required to evaluate how evenly pressure can be distributed using the hybrid-MCP concept.

The existing vehicle designs exhibit a high level of coupling. For instance the coupling in the suspension and steering systems manifests itself through the change in wheel alignment parameters (WAP) due to suspension travel. This change in the WAP causes directional instability and tire-wear. The approach of the industry to solve this problem has been twofold. The first approach has been optimization of suspension link lengths to reduce the change in WAP to zero. Since this is not possible with the existing architecture, the solution used is the optimization of the spring stiffness K to get a compromise solution for comfort (which requires significant suspension travel and hence a soft spring) and directional stability (which demands least possible change in wheel alignment parameters and hence a stiff spring).

Semi-solid metal (SSM) casting has long been identified as a high-volume process for producing safety-critical and structural automotive castings, but cost and complexity issues have limited its widespread commercial acceptance. Rheocasting, an SSM process that creates semi-solid slurry directly from liquid metal, eliminates the cost disadvantages of the process. However, the majority of rheocasting processes are complex and difficult to operate in the foundry environment. Recent work at MIT has led to the fundamental discovery that application of heat removal and convection as a molten alloy cools through the liquidus creates a non-dendritic, semi-solid slurry. A new process based on this understanding, S.S.R.™ (Semi-Solid Rheocasting), simplifies the rheocasting process by controlling heat removal and convection of an alloy during cooling using an external device. Solution heat treatable castings have been produced in a horizontal die casting machine with the S.S.R.™ process.

The US Air Force (USAF) has evolved a policy for the acquisition of fighter jet engines (FJE). In the 1970s and 1980s that policy placed a premium on FJE performance primarily measured by the metric: thrust/engine weight. In the 1990s, the USAF policy changed from an emphasis on performance to reduced life-cycle cost with a premium on sustainment. This paper reports the results of a study of how the USAF and Corporation Alpha (Alpha) have adapted their processes, practices, and policies to design, develop, manufacture, test, and sustain a family of FJEs. Each member of the family of FJEs is sequentially linked relative to insertion of technology designed to reduce sustainment costs. In addition to the technology linkages, the development of the family of FJEs selected for this case study is also tracked relative to US Department of Defense and USAF policy and industry design, build, and maintain processes, methods, and tools.

Extravehicular activity (EVA) is investigated through experiments testing an actual extravehicular mobility unit (EMU) performing several EVA tasks in the laboratory, and a dynamic model of the EMU space suit is developed. Building directly on earlier work in EVA simulation, the space suit model was created from mass, inertia, and performance data to augment the unsuited 12-segment human model used in previous studies. A modified Preisach model was used to mathematically describe the hysteretic torque characteristics of joints in a pressurized space suit, and implemented numerically based on observed suit parameters. Computational simulations, based loosely on a 1995 EVA involving manipulation of the Spartan astrophysics payload, were performed to observe the effect of suit constraints on simulated astronaut performance.

New three-dimensional printing technology (3DP) developed at MIT was tried as a manufacturing method to fabricate ceramic preforms for a discontinuously reinforced metal matrix composites. Minor modifications to the “legacy” 3DP technology allowed to produce such preforms successfully. Preforms were then infiltrated with liquid aluminum resulting in composite materials as strong as produced via conventional methods. Net shape connecting rod preforms were 3D-printed and used to produce composite connecting rods without building any molds or tooling using novel Tool-less Mold™ technology.

Low volume manufacturing has become increasingly important for the automotive industry. Globalization trends have led automakers and their suppliers to operate in developing regions where minimum efficient scales can not always be achieved. With proper maintenance, standard cast iron stamping tools can be used to produce millions of parts, but require large investments. Thus at high production volumes, the impact of the tooling investment on individual piece costs is minimized. However, at low volumes there is a substantial cost penalty. In light of the trends towards localized manufacturing and relatively low demands in some developing markets, low cost stamping tools are needed. Several alternate tooling technologies exist, each of which require significantly lower initial investments, but suffer from greatly reduced tool lives. However, the use of these technologies at intermediate to high volumes requires multiple tool sets thus eliminating their cost advantage.

Recent industry trends have resulted in growing interest among automakers in low to medium volume manufacturing. The expansion of automobile production into developing economies and the desire to produce specialized vehicles for niche markets have pressed the automakers to find cost effective solutions for manufacturing at low volumes, particularly with regard to sheet metal forming. Conventional high volume stamping operations rely heavily on achieving minimum scale economies which occur at about 200,000 parts per year. These scale economies are mainly dictated by the efficient use of the standard, expensive cast iron dies. These dies can cost well over one million dollars depending on the part, and in return offer tool lives over 5 million strokes. Die investment can be reduced by changing the stamping process technology. Hydro-mechanical forming has been proposed as a promising low volume alternative to conventional stamping.

The quest for higher efficiency and performance of automotive vehicles requires application of materials with high strength, stiffness and lower weight in their construction. Particulate-reinforced aluminum-matrix composites are cost-competitive materials, which can meet these requirements. MMCC, Inc. has been optimizing particulate-reinforced alloy systems and developing the Advanced Pressure Infiltration Casting (APIC™) process for the manufacture of components from these materials. This paper discusses the results of a recent study in which composites reinforced with 55 vol.% alumina were cast using two sizes of alumina particulate and eight different matrix alloys based on Al-4.5 wt.% Cu with varying amounts of silicon and magnesium. Optimum heat treatments for each alloy were determined utilizing microhardness studies. The tensile strength and fracture toughness were evaluated as a function of alloy chemistry, particulate size, and heat treatment.

A novel system for the forming of three dimensional sheet metal parts is described that can form a variety of part shapes without the need for fixed tooling, and given only geometry (CAD) information about the desired part. The central elements of this system are a tooling concept based on a programmable discrete die surface and closed-loop shape control. The former give the process the degrees of freedom to change shape rapidly, and the latter is used to insure that the correct shape is formed with a minimum of forming trials. A 540 kN (60 ton) lab press has been constructed with a 0.3 m (12 in) square pair of discrete tools that can be rapidly re-shaped between forming trials. The shape control system uses measured part shapes to determine a shape error and to correct the tooling shape. This correction is based on a unique “Deformation Transfer Function” approach using a spatial frequency decomposition of the surface.

Zinc coating integrity, composition, thickness, roughness, and the presence of Fe-Zn intermetallics are being investigated with regard to the mechanisms of weld nugget formation. This information is being used in conjunction with the optimization of the weld process parameters; such as upsloping, down-sloping, preheating, postheating, and double pulsing, to provide the widest range of acceptable welding conditions. Dynamic inspection monitoring of the welding current, voltage, force, and nugget displacement is being used to follow the progression of nugget formation and to assist in the evaluation of optimum process and material characteristics. It has been found that hot-dipped galvanized materials with coatings which have a very thin Fe-Zn alloy layer, have a wider range of acceptable welding conditions than the commercial galvannealed products, which have a fully alloyed Fe-Zn coating.